Mine is: Eating foods that are in their most natural state. I have been doing this for 10 years now and have medical proof it worked for me. Last year I was tested by an internal medicine specialist and was told I was the healthiest person tested ever. He said he wished he had my health. Imagine being told you have set the new standard in your country.

But Jim, with the greatest respect, you don't have 'medical proof' that eating clean worked at all.

You have medical proof that you're super-healthy (and it must be fantastic to hear that!). You don't have medical proof that this is the result of your diet. There could be any number of reasons for your super-healthiness. You might feel very strongly that the diet is responsible for your health, but you can't know it.

Quite often someone has all sorts of health problems for years, makes some sort of change (e.g. cutting out food X) and starts feeling better. They then naturally assume that the change caused the improvement. One problem with this assumption is that the body can and does heal various problems on its own, and at unpredictable intervals. The second is that people rarely make a single change in their lifestyle at once. For example, they change their diet, and lose weight and change their training andfeel more positive because they're making changes. And so on.

An example of the body sorting itself out: when I was in my mid 20s, I had a fall. It was only about four feet, but I landed ona flat piece of rock. I hurt my knee and hip, but weirdly, after they recovered, I had arthritis-like symptoms everywhere. Some days I could barely straighten my fingers. This went on for months. It was very difficult to source any medical help because I was travelling through India and South East Asia. Eventually, it disappeared, and pretty quickly. I've no idea to this day how a fall can cause that or why the symptoms went. But supposing I had had the internet in those days, googled my symptoms, and 'discovered' it was all caused by eating too little XYZ or too much ABC, or that I could 'cure' it by wearing a copper bracelet. If I had made a particular change and then slowly got better, I'm sure for the rest of my life I would have been convinced that it was the change that improved my health.

The point of my long-winded post is that we have to be really careful about using 'it worked for me' statements as evidence. If you changed your diet and good things started happeneing, then (a) excellent, good for you and (b) maybe it was down to the diet. But that's a long way from proof.